That the pungent ingredient of black and long pepers, piperine, modulates the catalytic activity of cytochrome P450, using selective in vivo probes, the effects of acute oral dosing w/piperine, on individual cytochrome P450 (CYP1A, CYP2A6, CYP2C9, CYP2C19,CYP2D6, CYP2E1 and CYP3A) in healthy subjects.